Linear compressor and refrigerator including a linear compressor

ABSTRACT

A linear compressor and a refrigerator including a linear compressor is provided. The linear compressor may include a shell including a suction inlet, a cylinder provided in the shell to define a compression space for a refrigerant, a piston reciprocated in an axial direction within the cylinder, a discharge valve provided at one side of the cylinder to selectively discharge the refrigerant compressed in the compression space, at least one nozzle disposed in the cylinder to introduce at least a portion of the refrigerant discharged through the discharge valve into the cylinder, and at least one filter provided in the shell. The at least one filter may be disposed in a refrigerant passage defined from the suction inlet to the at least one nozzle via the discharge valve. Foreign substances or oil contained in the refrigerant introduced into the at least one nozzle may be filtered while passing through the at least one filter.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority under 35 U.S.C. §119 to KoreanApplication No. 10-2014-0078763, filed in Korea on Jun. 26, 2014, whoseentire disclosure is hereby incorporated by reference.

BACKGROUND

1. Field

A linear compressor and a refrigerator including a linear compressor aredisclosed herein.

2. Background

In general, compressors are machines that receive power from a powergeneration device, such as an electric motor or turbine, to compressair, a refrigerant, or various working gases, thereby increasing inpressure. Compressors are being widely used in home appliances, such asrefrigerators or air conditioners, or industrial fields.

Compressors may be largely classified into reciprocating compressors, inwhich a compression space into and from which a working gas is suctionedand discharged, is defined between a piston and a cylinder to allow thepiston to be linearly reciprocated in the cylinder, thereby compressingthe working gas; rotary compressors, in which a compression space intoand from which a working gas is suctioned or discharged, is definedbetween a roller that eccentrically rotates and a cylinder to allow theroller to eccentrically rotate along an inner wall of the cylinder,thereby compressing the working gas; and scroll compressors, in which acompression space into and from which a working gas is suctioned anddischarged, is defined between an orbiting scroll and a fixed scroll tocompress the working gas while the orbiting scroll rotates along thefixed scroll. In recent years, a linear compressor, which is directlyconnected to a drive motor and in which a piston is linearlyreciprocated, to improve compression efficiency without mechanical lossdue to movement conversion and having a simple structure, is beingwidely developed. The linear compressor may suction and compress aworking gas, such as a refrigerant, while the piston is linearlyreciprocated in a sealed shell by a linear motor and then discharge theworking gas.

The linear motor is configured to allow a permanent magnet to bedisposed between an inner stator and an outer stator. The permanentmagnet may be linearly reciprocated by an electromagnetic force betweenthe permanent magnet and the inner (or outer) stator. Also, as thepermanent magnet operates in a state in which the permanent magnet isconnected to the piston, the refrigerant may suctioned and compressedwhile the piston is linearly reciprocated within the cylinder, and then,may be discharged.

The present Applicant has filed for a patent (hereinafter, referred toas a “prior art document”) and then registered the patent with respectto the linear compressor, as Korean Patent No. 10-1307688, filed inKorea on Sep. 5, 2013, and entitled “linear compressor”, which is herebyincorporated by reference. The linear compressor according to the priorart document includes a shell to accommodate a plurality of components.A vertical height of the shell may be somewhat high, as illustrated inthe prior art document. An oil supply assembly to supply oil between acylinder and a piston may be disposed within the shell. When the linearcompressor is provided in a refrigerator, the linear compressor may bedisposed in a machine room provided at a rear side of the refrigerator.

In recent years, a major concern of customers is increasing an innerstorage space of the refrigerator. To increase the inner storage spaceof the refrigerator, it may be necessary to reduce a volume of themachine room. To reduce the volume of the machine room, it may beimportant to reduce a size of the linear compressor.

However, as the linear compressor disclosed in the prior art documenthas a relatively large volume, the linear compressor in the prior artdocument is not applicable to a refrigerator, for which an increase inthe inner storage space is sought. To reduce the size of the linearcompressor, it may be necessary to reduce a size of a main component ofthe compressor. In this case, the compressor may deteriorate inperformance.

To compensate for the deteriorated performance of the compressor, it maybe necessary to increase a drive frequency. However, the more the drivefrequency of the compressor is increased, the more a friction force dueto oil circulating in the compressor is increased, deterioratingperformance of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described in detail with reference to the followingdrawings in which like reference numerals refer to like elements, andwherein:

FIG. 1 is a schematic diagram of a refrigerator according to anembodiment;

FIG. 2 is a cross-sectional view of a dryer of the refrigerator of FIG.1;

FIG. 3 is a cross-sectional view of a linear compressor of therefrigerator of FIG. 1;

FIG. 4 is a cross-sectional view of a suction muffler of the linearcompressor of FIG. 3;

FIG. 5 is a view illustrating a state in which a first filter is coupledto the suction muffler of FIG. 4;

FIG. 6 is a partial cross-sectional view illustrating a position of asecond filter according to an embodiment;

FIG. 7 is an exploded perspective view of a cylinder and a frame of thelinear compressor of FIG. 3;

FIG. 8 is an exploded perspective of the frame of FIG. 7;

FIG. 9 is a cross-sectional view illustrating a state in which thecylinder and a piston are coupled to each other according to anembodiment;

FIG. 10 is a view of the cylinder according to an embodiment;

FIG. 11 is an enlarged cross-sectional view of portion A of FIG. 9;

FIG. 12 is a cross-sectional view illustrating a refrigerant flow in thelinear compressor of FIG. 3; and

FIG. 13 is a cross-sectional view illustrating a position of a secondfilter according to another embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described with reference to theaccompanying drawings. Embodiments may, however, be embodied in manydifferent forms and should not be construed as being limited to theembodiments set forth herein; rather, alternate embodiments fallingwithin the spirit and scope will fully convey the concept to thoseskilled in the art.

FIG. 1 is a schematic diagram of a refrigerator according to anembodiment. Referring to FIG. 1, a refrigerator 10 according to anembodiment may include a plurality of devices to drive a refrigerationcycle.

In detail, the refrigerator 10 may include a compressor 100 to compressa refrigerant, a condenser 20 to condense the refrigerant compressed inthe compressor 100, a dryer 200 to remove moisture, foreign substances,or oil from the refrigerant condensed in the condenser 20, an expansiondevice 30 to decompress the refrigerant having passed through the dryer200, and an evaporator 40 to evaporate the refrigerant decompressed inthe expansion device 30. The refrigerator 10 may further include acondensation fan 25 to blow air toward the condenser 20, and anevaporation fan 45 to blow air toward the evaporator 40.

The compressor 100 may be a linear compressor in which a piston may bedirectly connected to a motor to compress the refrigerant while thepiston is linearly reciprocated within a cylinder. The expansion device30 may include a capillary tube having a relatively small diameter.

A liquid refrigerant condensed in the condenser 20 may be introducedinto the dryer 200. A gaseous refrigerant may be partially contained inthe liquid refrigerant. A filter to filter the liquid refrigerantintroduced into the dryer 200 may be provided in the dryer 200.Hereinafter, components of the dryer 200 will be described withreference to the accompanying drawings.

FIG. 2 is a cross-sectional view of a dryer of the refrigerator ofFIG. 1. Referring to FIG. 2, the dryer 200 according to an embodimentmay include a dryer body 210 to define a flow space for the refrigerant,a refrigerant inflow 211 disposed on or at one or a first side of thedryer body 210 to guide introduction of the refrigerant, and arefrigerant discharge 215 disposed on or at the other or a second sideof the dryer body 210 to guide discharge of the refrigerant. Forexample, the dryer body 210 may have a long cylindrical shape.

Dryer filters 220, 230, and 240 may be provided in the dryer body 210.In detail, the dryer filters 220, 230, and 240 may include a first dryerfilter 220 disposed adjacent to the refrigerant inflow 211, a thirddryer filter 240 spaced apart from the first dryer filter 220 anddisposed adjacent to the refrigerant discharge 215, and a second dryerfilter 230 disposed between the first dryer filter 220 and the thirddryer filter 240.

The first dryer filter 220 may be disposed adjacent to an inside of therefrigerant inflow 211, that is, disposed at a position closer to therefrigerant inflow 211 than the refrigerant discharge 215.

The first dryer filter 220 may have an approximately hemisphericalshape. An outer circumferential surface of the first dryer filter 220may be coupled to an inner circumferential surface of the dryer body210. A plurality of through holes 221 to guide flow of the refrigerantmay be defined in the first dryer filer 220. A foreign substance havinga relatively large volume may be filtered by the first dryer filter 220.

The second dryer filter 230 may include a plurality of adsorbents 231.Each of the adsorbents 231 may be a grain having a predetermined size.The adsorbent 231 may be a molecular sieve and have a predetermined sizeof about 5 mm to about 10 mm.

A plurality of holes may be defined in the adsorbent 231. Each of theplurality of holes may have a size similar to a size of oil (about 10Å). The hole may have a size greater than a size (about 2.8 Å to about3.2 Å) of the moisture and (about 4.0 Å in case of R134a, and about 4.3Å in the case of R600a) of the refrigerant. The term “oil” may refer toa working oil or cutting oil injected when components of therefrigeration cycle are manufactured or processed.

The refrigerant and moisture passing through the first dryer filter 220may be easily discharged even though the refrigerant and moisture areeasily introduced into the plurality of holes while passing through theadsorbents 231. Thus, the refrigerant and moisture may not be easilyadsorbed onto the adsorbents 231. However, if the oil is introduced intothe plurality of holes, the oil may not be easily discharged, and thus,may be maintained in a state in which the oil is adsorbed onto theadsorbents 231.

For example, the adsorbent 231 may include a BASF 13X molecular sieve. Ahole defined in the BASF 13X molecular sieve may have a size of about 10Å (1 nm), and the BASF 13X molecular sieve may be expressed as achemical formula: Na2O.Al2O3.mSiO2.nH20 (m≦2.35).

The oil contained in the refrigerant may be adsorbed into the pluralityof adsorbents 231 while passing through the second dryer filter 230.Alternatively, the second dryer filter 230 may include an oil adsorbentpaper or an adsorbent having a felt, instead of the plurality ofadsorbents each having a grain shape.

The third dryer filter 240 may include a coupling portion 241 coupled tothe inner circumferential surface of the dryer body 210, and a mesh 242that extends from the coupling portion 241 toward the refrigerantdischarge 215. The third dryer filer 240 may be a mesh filter. A foreignsubstance having a fine size contained in the refrigerant may befiltered by the mesh 242.

Each of the first dryer filter 220 and the third dryer filter 240 mayserve as a support to locate the plurality of adsorbents 231 within thedryer body 210. That is, discharge of the plurality of adsorbents 231from the dryer 200 may be restricted by the first and third dryerfilters 220 and 240.

As described above, the filters may be provided in the dryer 200 toremove foreign substances or oil contained in the refrigerant, therebyimproving reliability of the refrigerant that acts as a gas bearing.

FIG. 3 is a cross-sectional view of a linear compressor of therefrigerant in FIG. 1. Referring to FIG. 3, the linear compressor 100according to an embodiment may include a shell 101 having anapproximately cylindrical shape, a first cover 102 coupled to a firstside of the shell 101, and a second cover 103 coupled to a second sideof the shell 101. For example, the linear compressor 100 may be laid outin a horizontal direction. The first cover 102 may be coupled to a rightor first lateral side of the shell 101, and the second cover 103 may becoupled to a left or second lateral side of the shell 101 with referenceto FIG. 3. Each of the first and second covers 102 and 103 may beunderstood as one component of the shell 101.

The linear compressor 100 may further include a cylinder 120 provided inthe shell 101, a piston 130 linearly reciprocated within the cylinder120, and a motor assembly that serves as a linear motor to apply a driveforce to the piston 130. When the motor assembly 140 operates, thepiston 130 may be linearly reciprocated at a high rate. The linearcompressor 100 according to this embodiment may have a drive frequencyof about 100 Hz, for example.

The linear compressor 100 may include a suction inlet 104, through whichthe refrigerant may be introduced, and a discharge outlet 105, throughwhich the refrigerant compressed in the cylinder 120 may be discharged.The suction inlet 104 may be coupled to the first cover 102, and thedischarge outlet 105 may be coupled to the second cover 103.

The refrigerant in suctioned through the suction inlet 104 may flow intothe piston 130 via a suction muffler 150. Thus, while the refrigerantpasses through the suction muffler 150, noise may be reduced. Thesuction muffler 150 may include a first muffler 151 coupled to a secondmuffler 153. At least a portion of the suction muffler 150 may bedisposed within the piston 130.

The piston 130 may include a piston body 131 having an approximatelycylindrical shape, and a piston flange 132 that extends from the pistonbody 131 in a radial direction. The piston body 131 may be reciprocatedwithin the cylinder 120, and the piston flange 132 may be reciprocatedoutside of the cylinder 120.

The piston 130 may be formed of an aluminum material, such as aluminumor an aluminum alloy, which is a nonmagnetic material. As the piston 130may be formed of the aluminum material, a magnetic flux generated in themotor assembly 140 may not be transmitted into the piston 130, and thus,may be prevented from leaking outside of the piston 130. The piston 130may be manufactured by a forging process, for example.

The cylinder 120 may be formed of an aluminum material, such as aluminumor an aluminum alloy, which is a nonmagnetic material. The cylinder 120and the piston 130 may have a same material composition, that is, a samekind of material and composition.

As the piston cylinder 120 may be formed of the aluminum material, amagnetic flux generated in the motor assembly 200 may not be transmittedinto the cylinder 120, and thus, may be prevented from leaking outsideof the cylinder 120. The cylinder 120 may be manufactured by anextruding rod processing process, for example.

Also, as the piston 130 may be formed of the same material as thecylinder 120, the piston 130 may have a same thermal expansioncoefficient as the cylinder 120. When the linear compressor 100operates, a high-temperature (a temperature of about 100° C.)environment may be created within the shell 100. Thus, as the piston 130and the cylinder 120 may have the same thermal expansion coefficient,the piston 130 and the cylinder 120 may be thermally deformed by a samedegree. As a result, the piston 130 and the cylinder 120 may bethermally deformed with sizes and in directions different from eachother to prevent the piston 130 from interfering with the cylinder 120while the piston 130 moves.

The cylinder 120 may be configured to accommodate at least a portion ofthe suction muffler 150 and at least a portion of the piston 130. Thecylinder 120 may have a compression space P, in which the refrigerantmay be compressed by the piston 130. A suction hole 133, through whichthe refrigerant may be introduced into the compression space P, may bedefined in or at a front portion of the piston 130, and a suction valve135 to selectively open the suction hole 133 may be disposed on or at afront side of the suction hole 133. A coupling hole, to which apredetermined coupling member may be coupled, may be defined in anapproximately central portion of the suction valve 135.

A discharge cover 160 that defines a discharge space or dischargepassage for the refrigerant discharged from the compression space P, anda discharge valve assembly 161, 162, and 163 coupled to the dischargecover 160 to selectively discharge the refrigerant compressed in thecompression space P may be provided at a front side of the compressionspace P. The discharge valve assembly 161, 162, and 163 may include adischarge valve 161 to introduce the refrigerant into the dischargespace of the discharge cover 160 when a pressure within the compressionspace P is above a predetermined discharge pressure, a valve spring 162disposed between the discharge valve 161 and the discharge cover 160 toapply an elastic force in an axial direction, and a stopper 163 torestrict deformation of the valve spring 162.

The term “compression space P” may be refer to a space defined betweenthe suction valve 135 and the discharge valve 161. The term “axialdirection” may refer a direction in which the piston 130 may bereciprocated, that is, a transverse direction in FIG. 3. Also, in theaxial direction, a direction from the suction inlet 104 toward thedischarge outlet 105, that is, a direction in which the refrigerantflows, may be referred to as a “frontward direction”, and a directionopposite to the frontward direction may be referred to as a “rearwarddirection”. On the other hand, the term “radial direction” may refer toa direction perpendicular to the direction in which the piston 130 isreciprocated, that is, a vertical direction in FIG. 3.

The stopper 163 may be seated on the discharge cover 160, and the valvespring 162 may be seated at a rear side of the stopper 163. Thedischarge valve 161 may be coupled to the valve spring 162, and a rearportion or rear surface of the discharge valve 161 may be supported by afront surface of the cylinder 120. The valve spring 162 may include aplate spring, for example.

The suction valve 135 may be disposed on or at a first side of thecompression space P, and the discharge valve 161 maybe disposed on or ata second side of the compression space P, that is, a side opposite ofthe suction valve 135.

While the piston 130 is linearly reciprocated within the cylinder 120,when the pressure of the compression space P is below the predetermineddischarge pressure and a predetermined suction pressure, the suctionvalve 135 may be opened to suction the refrigerant into the compressionspace P. On the other hand, when the pressure of the compression space Pis above the predetermined suction pressure, the refrigerant may becompressed in the compression space P in a state in which the suctionvalve 135 is closed.

When the pressure of the compression space P is above the predetermineddischarge pressure, the valve spring 162 may be deformed to open thedischarge valve 161. The refrigerant may be discharged from thecompression space P into the discharge space of the discharge cover 160.

The refrigerant flowing into the discharge space of the discharge cover160 may be introduced into a loop pipe 165. The loop pipe 165 may becoupled to the discharge cover 160 to extend to the discharge outlet105, thereby guiding the compressed refrigerant in the discharge spaceinto the discharge outlet 105. For example, the loop pipe 165 may have ashape which is wound in a predetermined direction and extends in arounded shape. The loop pipe 165 may be coupled to the discharge outlet105.

The linear compressor 100 may further include a frame 110. The frame 110may fix the cylinder 120 and be coupled to the cylinder 120 by aseparate coupling member, for example. The frame 110 may be disposed tosurround the cylinder 120. That is, the cylinder 120 may be accommodatedwithin the frame 110. The discharge cover 172 may be coupled to a frontsurface of the frame 110.

At least a portion of the high-pressure gaseous refrigerant dischargedthrough the open discharge valve 161 may flow toward an outercircumferential surface of the cylinder 120 through a space formed at aportion at which the cylinder 120 and the frame 110 are coupled to eachother. The refrigerant may be introduced into the cylinder 120 throughone or more gas inflow (see reference numeral 122 of FIG. 7) and one ormore nozzle (see reference numeral 123 of FIG. 11), which may be definedin the cylinder 120. The introduced refrigerant may flow into a spacedefined between the piston 130 and the cylinder 120 to allow an outercircumferential surface of the piston 130 to be spaced apart from aninner circumferential surface of the cylinder 120. Thus, the introducedrefrigerant may serve as a “gas bearing” that reduces friction betweenthe piston 130 and the cylinder 120 while the piston 130 isreciprocated.

The motor assembly 140 may include outer stators 141, 143, and 145 fixedto the frame 110 and disposed to surround the cylinder 120, an innerstator 148 disposed to be spaced inward from the outer stators 141, 143,and 145, and a permanent magnet 146 disposed in a space between theouter stators 141, 143, and 145 and the inner stator 148. The permanentmagnet 146 may be linearly reciprocated by a mutual electromagneticforce between the outer stators 141, 143, and 145 and the inner stator148. Also, the permanent magnet 146 may be a single magnet having onepolarity, or a plurality of magnets having three polarities.

The permanent magnet 146 may be coupled to the piston 130 by aconnection member 138. In detail, the connection member 138 may becoupled to the piston flange 132 and be bent to extend toward thepermanent magnet 146. As the permanent magnet 146 is reciprocated, thepiston 130 may be reciprocated together with the permanent magnet 146 inthe axial direction.

The motor assembly 140 may further include a fixing member 147 to fixthe permanent magnet 146 to the connection member 138. The fixing member147 may be formed of a composition in which glass fiber or carbon fiberis mixed with a resin. The fixing member 147 may surround an outside ofthe permanent magnet 146 to firmly maintain a coupled state between thepermanent magnet 146 and the connection member 138.

The outer stators 141, 143, and 145 may include coil winding bodies 143and 145, and a stator core 141. The coil winding bodies 143 and 145 mayinclude a bobbin 143, and a coil 145 wound in a circumferentialdirection of the bobbin 145. The coil 145 may have a polygonalcross-section, for example, a hexagonal cross-section. The stator core141 may be manufactured by stacking a plurality of laminations in thecircumferential direction and be disposed to surround the coil windingbodies 143 and 145.

A stator cover 149 may be disposed on or at one side of the outerstators 141, 143, and 145. A first side of the outer stators 141, 143,and 145 may be supported by the frame 110, and a second side of theouter stators 141, 143, and 145 may be supported by the stator cover149. The inner stator 148 may be fixed to a circumference of the frame110. In the inner stator 148, a plurality of laminations may be stackedin the circumferential direction outside of the cylinder 120.

The linear compressor 100 may further include a support 137 to supportthe piston 130, and a back cover 170 spring-coupled to the support 137.The support 137 may be coupled to the piston flange 132 and theconnection member 138 by a predetermined coupling member, for example.

A suction guide 155 may be coupled to a front portion of the back cover170. The suction guide 155 may guide the refrigerant suctioned inthrough the suction inlet 104 to introduce the refrigerant into thesuction muffler 150.

The linear compressor 100 may further include a plurality of springs 176which are adjustable in natural frequency to allow the piston 130 toperform a resonant motion. The plurality of springs 176 may include afirst spring supported between the support 137 and the stator cover 149,and a second spring supported between the support 137 and the back cover170.

The linear compressor 100 may additionally further include plate springs172 and 174, respectively, disposed on both sides of the shell 101 toallow inner components of the compressor 100 to be supported by theshell 101. The plate springs 172 and 174 may include a first platespring 172 coupled to the first cover 102, and a second plate spring 174coupled to the second cover 103. For example, the first plate spring 172may be fitted into a portion at which the shell 101 and the first cover102 are coupled to each other, and the second plate spring 174 may befitted into a portion at which the shell 101 and the second cover 103are coupled to each other.

FIG. 4 is a cross-sectional view of a suction muffler of the linearcompressor of FIG. 1. FIG. 5 is a view illustrating a state in which afirst filter is coupled to the suction muffler of FIG. 4.

Referring to FIGS. 4 and 5, the suction muffler 150 according to thisembodiment may include the first muffler 151, the second muffler 153coupled to the first muffler 151, and a first filter 310 supported bythe first and second mufflers 151 and 153. A flow space, in which therefrigerant may flow, may be defined in each of the first and secondmufflers 151 and 153. The first muffler 151 may extend from an inside ofthe suction inlet 104 in a direction of the discharge outlet 105, and atleast a portion of the first muffler 151 may extend inside of thesuction guide 155. The second muffler 153 may extend from the firstmuffler 151 inside of the piston body 131.

The first filter 310 may be disposed in the flow space to filter foreignsubstances. The first filter 310 may be formed of a material having amagnetic property. Thus, foreign substances contained in therefrigerant, in particular, metallic substances, may be easily filtered.

For example, the first filter 310 may be formed of stainless steel, andthus, may have a magnetic property to prevent the first filter 310 fromrusting. Alternatively, the first filter 310 may be coated with amagnetic material, or a magnet may be attached to a surface of the firstfilter 310.

The first filter 310 may be provided as a mesh-type structure having aplurality of filter holes and have an approximately circular plateshape. Each of the filter holes may have a diameter or width less than apredetermined diameter or width, that is, a predetermined size. Forexample, the predetermined size may be about 25 μm.

The first muffler 151 and the second muffler 153 may be assembled witheach other using a press-fit manner, for example. The first filter 310may be fitted into a portion into which the first and second mufflers151 and 153 are press-fitted and then be assembled. In detail, a groove151 a, to which at least a portion of the second muffler 153 may becoupled, may be defined in the first muffler 151. The second muffler 153may include a protrusion 153 a inserted into the groove 151 a of thefirst muffler 151.

The first filter 310 may be supported by the first and second mufflers151 and 153 in a state in which both sides of the first filter 310 aredisposed between the groove 151 a and the protrusion 153 a. In the statein which the first filter 310 is disposed between the first and secondmufflers 151 and 153, when the first and second mufflers 151 and 153move in a direction that approach each other and then are press-fitted,both sides of the first filter 310 may be inserted and fixed between thegroove 151 a and the protrusion 153 a.

As described above, as the first filter 310 may be provided on thesuction muffler 150, a foreign substance having a size greater than apredetermined size of the refrigerant suctioned in through the suctioninlet 104 may be filtered by the first filter 310. Thus, the firstfilter 310 may filter the foreign substance from the refrigerant actingas the gas bearing between the piston 130 and the cylinder 120 toprevent the foreign substance from being introduced into the cylinder120. Also, as the first filter 310 is firmly fixed to the portion atwhich the first and second mufflers 151 and 153 are coupled orpress-fitted, separation of the first filter 310 from the suctionmuffler 150 may be prevented.

In this embodiment, although the groove 151 a is defined in the firstmuffler 151, and the protrusion 153 a is disposed on the second muffler153, embodiments are not limited thereto. For example, the protrusion153 a may be disposed on the first muffler 151, and the groove 151 a maybe defined in the second muffler 153.

FIG. 6 is a partial cross-sectional view illustrating a position of asecond filter according to an embodiment. FIG. 7 is an explodedperspective view of a cylinder and a frame of the linear compressor ofFIG. 3. FIG. 8 is an exploded perspective of the frame of FIG. 7.

Referring to FIGS. 6 to 8, the linear compressor 100 according to anembodiment may include a second filter 320 disposed between the frame110 and the cylinder 120 to filter a high-pressure gas refrigerantdischarged through the discharge valve 161. The second filter 320 may bedisposed on or at a portion of a coupled surface at which the frame 110and the cylinder 120 are coupled to each other.

In detail, the cylinder 120 may include a cylinder body 121 having anapproximately cylindrical shape, and a cylinder flange 125 that extendsfrom the cylinder body 121 in a radial direction. The cylinder body 121may include at least one gas inflow 122, through which the dischargedgas refrigerant may be introduced. The gas inflow 122 may be formed in acircular shape along a circumferential surface of the cylinder body 121.

The at least one gas inflow 122 may include a plurality of gas inflows122. The plurality of gas inflows 122 may include gas inflows (seereference numerals 122 a and 122 b of FIG. 10) disposed on a first sidewith respect to a center or central portion 121 c of the cylinder body121 in an axial direction, and a gas inflow (see reference numeral 122 cof FIG. 10) disposed on a second side with respect to the center orcentral portion 121 c of the cylinder body 121 in the axial direction.

One or more coupling portion 126 coupled to the frame 110 may bedisposed on the cylinder flange 125. Each coupling portion 126 mayprotrude outward from an outer circumferential surface of the cylinderflange 125, and be coupled to a cylinder coupling hole 118 of the frame110 by a predetermined coupling member, for example.

The cylinder flange 125 may have a seat surface 127 seated on the frame110. The seat surface 127 may be a rear surface of the cylinder flange125 that extends from the cylinder body 121 in a radial direction.

The frame 110 may include a frame body 111 that surrounds the cylinderbody 121, and a cover coupling portion 115 that extends in a radialdirection of the frame body and is coupled to the discharge cover 160.

The cover coupling portion 115 may have a plurality of cover couplingholes 116, in which the coupling member coupled to the discharge cover160 may be inserted, and a plurality of the cylinder coupling holes 118,in which the coupling member coupled to the cylinder flange 125 may beinserted. The plurality of cylinder coupling holes 118 may be defined atpositions recessed somewhat from the cover coupling portion 115.

The frame 110 may have a recess 117 recessed backward from the covercoupling portion 115 to allow the cylinder flange 125 to be insertedtherein. That is, the recess 117 may be disposed to surround the outercircumferential surface of the cylinder flange 125. The recess 117 mayhave a recessed depth corresponding to a front to rear width of thecylinder flange 125.

A predetermined refrigerant flow space may be defined between an innercircumferential surface of the recess 117 and the outer circumferentialsurface of the cylinder flange 125. The high-pressure gas refrigerantdischarged from the discharge valve 161 may flow toward the outercircumferential surface of the cylinder body 121 via the refrigerantflow space. The second filter 320 may be disposed in the refrigerantflow space to filter the refrigerant.

In detail, a seat 113 having a stepped portion maybe disposed on or at arear end of the recess 117. The second filter 320 having a ring shapemay be seated on the seat 113.

In a state in which the second filter 320 is seated on the seat 113,when the cylinder 120 is coupled to the frame 110, the cylinder flange125 may push the second filter 320 from a front side of the secondfilter 320. That is, the second filter 320 may be disposed and fixedbetween the seat 113 of the frame 110 and the seat surface 127 of thecylinder flange 125.

The second filter 320 may prevent foreign substances in thehigh-pressure gas refrigerant discharged through the opened dischargevalve 161 from being introduced into the gas inflow 122 of the cylinder120 and be configured to adsorb oil contained in the refrigerantthereon. For example, the second filter 320 may include a felt formed ofpolyethylene terephthalate (PET) fiber or an adsorbent paper. The PETfiber may have superior heat-resistance and mechanical strength. Also, aforeign substance having a size of about 2 μm or more, which iscontained in the refrigerant, may be blocked.

The high-pressure gas refrigerant passing through the flow space definedbetween the inner circumferential surface of the recess 117 and theouter circumferential surface of the cylinder flange 125 may passthrough the second filter 320. In this process, the refrigerant may befiltered by the second filter 320.

FIG. 9 is a cross-sectional view illustrating a state in which thecylinder and a piston are coupled to each other according to anembodiment. FIG. 10 is a view of the cylinder according to anembodiment. FIG. 11 is an enlarged cross-sectional view of portion A ofFIG. 9.

Referring to FIGS. 9 to 11, the cylinder 120 according to an embodimentmay include the cylinder body 121 having an approximately cylindricalshape to form a first body end 121 a and a second body end 121 b, andthe cylinder flange 125 that extends from the second body end 121 b ofthe cylinder body 121 in a radial direction. The first body end 121 aand the second body end 121 b form both ends of the cylinder body 121with respect to the central portion 121 c of the cylinder body 121 in anaxial direction.

The cylinder body 121 may include a plurality of the gas inflows 122,through which at least a portion of the high-pressure gas refrigerantdischarged through the discharge valve 161 may flow. A third filter 330may be disposed in the plurality of gas inflows 122.

Each of the plurality of gas inflows 122 may be recessed from the outercircumferential surface of the cylinder body 121 by a predetermineddepth and width. The refrigerant may be introduced into the cylinderbody 121 through the plurality of gas inflows 122 and the nozzle 123.

The introduced refrigerant may be disposed between the outercircumferential surface of the piston 130 and the inner circumferentialsurface of the cylinder 120 to serve as the gas bearing with respect tomovement of the piston 130. That is, the outer circumferential surfaceof the piston 130 may be maintained in a state in which the outercircumferential surface of the piston 130 is spaced apart from the innercircumferential surface of the cylinder 120 by pressure of therefrigerant.

The plurality of gas inflows 122 may include first and second gasinflows 122 a and 122 b disposed on a first side with respect to thecentral portion 121 c in an axial direction of the cylinder body 121,and a third gas inflow 122 c disposed on a second side with respect tothe central portion 121 c in the axial direction. The first and secondgas inflows 122 a and 122 b may be disposed at positions closer to thesecond body end 121 b with respect to the central portion 121 c in theaxial direction of the cylinder body 121, and the third gas inflow 122 cmay be disposed at a position closer to the first body end 121 a withrespect to the central portion 121 c in the axial direction of thecylinder body 121. That is, the plurality of gas inflows 122 may beprovided in numbers which are not symmetrical to each other with respectto the central portion 121 c in the axial direction of the cylinder body121.

Referring to FIG. 10, the cylinder 120 may have a relatively high innerpressure at a side of the second body end 121 b, which may be closer toa discharge-side of the compressed refrigerant when compared to that ofthe first body end 121 a, which may be closer to a suction-side of therefrigerant. Thus, more gas inflows 122 may be provided at the side ofthe second body end 121 b to enhance a function of the gas bearing, andrelatively less gas inflows 122 may be provided at the side of the firstbody end 121 a.

The cylinder body 121 may further include one or more nozzle 123 thatextends from the plurality of gas inflows 122 toward the innercircumferential surface of the cylinder body 121. Each nozzle 123 mayhave a width or size less than a width or size of the gas inflow 122.

A plurality of the nozzles 123 may be provided along the gas inflow 122,which may extend in a circular shape. The plurality of nozzles 123 maybe disposed to be spaced apart from each other.

The plurality of nozzles 123 may each include an inlet 123 a connectedto the gas inflow 122, and an outlet 123 b connected to the innercircumferential surface of the cylinder body 121. Each nozzle 123 mayhave a predetermined length from the inlet 123 a toward the outlet 123b.

A recessed depth and width of each of the plurality of gas inflows 122and a length of the nozzle 123 may be determined to have adequatedimensions in consideration of a rigidity of the cylinder 120, an amountof third filter 330, or a intensity in pressure drop of the refrigerantpassing through the nozzle 123. For example, if the recessed depth andwidth of each of the plurality of gas inflows 122 are too large, or thelength of the nozzle 123 is too short, rigidity of the cylinder 120 maybe weak. On the other hand, if the recessed depth and width of each ofthe plurality of gas inflows 122 are too small, an amount of thirdfilter 330 provided in the gas inflow 122 may be too small. Also, if thelength of the nozzle 123 is too long, a pressure drop of the refrigerantpassing through the nozzle 123 may be too large, and it may be difficultto perform the function as the gas bearing.

The inlet 123 a of the nozzle 123 may have a diameter greater than adiameter of the outlet 123 b. In detail, if the diameter of the nozzle123 is too small, an amount of refrigerant, which may be introduced fromthe nozzle 123, of the high-pressure gas refrigerant discharged throughthe discharge valve 161 may be too large, increasing flow loss in thecompressor. On the other hand, if the diameter of the nozzle 123 is toosmall, the pressure drop in the nozzle 123 may increase, reducing aperformance of the gas bearing.

Thus, in this embodiment, the inlet 123 a of the nozzle 123 may have arelatively large diameter to reduce the pressure drop of the refrigerantintroduced into the nozzle 123. In addition, the outlet 123 b may have arelatively small diameter to control an inflow amount of gas bearingthrough the nozzle 123 to a predetermined value or less.

The third filter 330 may prevent a foreign substance having apredetermined size or more from being introduced into the cylinder 120and perform a function of adsorbing oil contained in the refrigerant.The predetermined size may be about 1 μm.

The third filter 330 may include a thread which is wound around the gasinflow 122. In detail, the thread may be formed of a polyethyleneterephthalate (PET) material and have a predetermined thickness ordiameter.

The thickness or diameter of the thread may be determined to haveadequate dimensions in consideration of a rigidity of the thread. If thethickness or diameter of the thread is too small, the thread may beeasily broken due to a very weak strength thereof. On the other hand, ifthe thickness or diameter of the thread is too large, a filtering effectwith respect to foreign substances may be deteriorated due to a verylarge pore in the gas inflow 122 when the thread is wound.

For example, the thickness or diameter of the thread maybe severalhundreds μm. The thread may be manufactured by coupling a plurality ofstrands of a spun thread having several tens μm to each other, forexample.

The thread may be wound several times, and an end of the thread may befixed with a knot, for example. A number of windings of the thread maybe adequately selected in consideration of the pressure drop of the gasrefrigerant and the filtering effect with respect to foreign substances.If the number of thread windings is too large, the pressure drop of thegas refrigerant may increase. On the other hand, if the number of threadwindings is too small, the filtering effect with respect to foreignsubstances may be reduced.

Also, a tension force of the wound thread may be adequately controlledin consideration of deformation of the cylinder and fixation of thethread. If the tension force is too large, deformation of the cylinder120 may occur. On the other hand, if the tension force is too small, thethread may not be adequately fixed to the gas inflow 122.

FIG. 12 is a cross-sectional view illustrating a refrigerant flow in thelinear compressor of FIG. 3. Referring to FIG. 12, refrigerant flow inthe linear compressor according to an embodiment will be describedhereinbelow.

Referring to FIG. 12, the refrigerant may be introduced into the shell101 through the suction inlet 104 and flow into the suction muffler 150through the suction guide 155. The refrigerant may be introduced intothe second muffler 153 via the first muffler 151 of the suction muffler150 to flow into the piston 130. In this way, suction noise of therefrigerant may be reduced.

A foreign substance having a predetermined size (about 25 μm) or more,which is contained in the refrigerant, may be filtered while passingthrough the first filter 310 provided on or in the suction muffler 150.The refrigerant within the piston 130 after passing though the suctionmuffler 150 may be suctioned into the compression space P through thesuction hole 133 when the suction valve 135 is opened.

When the refrigerant pressure in the compression space P is above thepredetermined discharge pressure, the discharge valve 161 may be opened.Thus, the refrigerant may be discharged into the discharge space of thedischarge cover 160 through the opened discharge valve 161, flow intothe discharge outlet 105 through the loop pipe 165 coupled to thedischarge cover 160, and be discharged outside of the compressor 100.

At least a portion of the refrigerant within the discharge space of thedischarge cover 160 may flow toward the outer circumferential surface ofthe cylinder body 121 via the space defined between the cylinder 120 andthe frame 110, that is, the inner circumferential surface of the recess117 of the frame 110 and the outer circumferential surface of thecylinder flange 125 of the cylinder 120. The refrigerant may passthrough the second filter 320 disposed between the seat surface 127 ofthe cylinder flange 125 and the seat 113 of the frame 110. In this way,a foreign substance having a predetermined size (about 2 μm) or more maybe filtered. Also, oil in the refrigerant may be adsorbed onto or intothe second filter 320.

The refrigerant passing through the second filter 320 may be introducedinto the plurality of gas inflows 122 defined in the outercircumferential surface of the cylinder body 121. Also, while therefrigerant passes through the third filter 330 provided on or in thegas inflows 122, a foreign substances having a predetermined size (about1 μm) or more, which is contained in the refrigerant, may be filtered,and oil contained in the refrigerant may be adsorbed.

The refrigerant passing through the third filter 330 may be introducedinto the cylinder 120 through the nozzle 123 and be disposed between theinner circumferential surface of the cylinder 120 and the outercircumferential surface of the piston 130 to space the piston 130 fromthe inner circumferential surface of the cylinder 120 (gas bearing). Asdescribed above, the high-pressure gas refrigerant may be bypassedwithin the cylinder 120 to serve as the gas bearing with respect to thepiston 130 which is reciprocated, thereby reducing abrasion between thepiston 130 and the cylinder 120. Also, as oil is not used for thebearing, friction loss due to oil may not occur even though thecompressor 100 operates at a high rate.

Also, as the plurality of filters may be provided on the path or passageof the refrigerant flowing in the compressor 100, foreign substancescontained in the refrigerant may be removed. Thus, the refrigerantacting as the gas bearing may be improved in reliability. Thus, it mayprevent the piston 130 or the cylinder 120 from being worn by foreignsubstances contained in the refrigerant. Also, as the oil contained inthe refrigerant may be removed by the plurality of filters, it mayprevent friction loss due to the oil from occurring.

The first, second, and third filters 310, 320, and 330 may be referredto as a “filter device” in that the filters 310, 320, and 330 filter therefrigerant that serves as the gas bearing. That is, the filter devicemay include at least one filter member disposed on or in the“refrigerant passage” from the suction inlet 104 to the nozzle 123 viathe discharge valve 161. Thus, foreign substances and oil in therefrigerant to be introduced into the nozzle 123 may be filtered whilepassing through the filter member.

Hereinafter, another embodiment will be described. This embodiment maybe the same as the previous embodiment except for an arrangement of asecond filter, and thus, different points therebetween will be mainlydescribed, and repetitive disclosure has been omitted.

FIG. 13 is a cross-sectional view of illustrating a position of a secondfilter is disposed according to another embodiment. Referring to FIG.13, linear compressor 100 according to this embodiment may include asecond filter 420 disposed between an outer circumferential surface ofcylinder flange 125 and an inner circumferential surface of recess 117of frame 110.

The second filter 420 may extend from a front end of the cylinder flangepart 125 in an axial direction of the compressor 100. Thus, at least aportion of a refrigerant discharged through discharge valve 161 may flowbackward along a longitudinal direction of the second filter 420.

For example, the second filter 420 may include a felt formed ofpolyethylene terephthalate (PET) fiber or an adsorbent paper. The PETfiber may have superior heat-resistance and mechanical strength. Also, aforeign substance having a size of about 2 μm or more, which may becontained in the refrigerant, may be blocked.

As the second filter 420 may be disposed in a refrigerant flow spacedefined between the cylinder 120 and the frame 110, foreign substancesin the refrigerant may be filtered, and oil contained in the refrigerantmay be adsorbed onto or into the second filter 420.

According to embodiments disclosed herein, a compressor including innercomponents may decrease in size to reduce a volume of a machine room ofa refrigerator and increase an inner storage space of the refrigerant.Also, a drive frequency of the compressor may increase to preventperformance of inner components from being deteriorated due to thedecreasing size thereof. In addition, as the gas bearing may be appliedbetween the cylinder and the piston, friction force occurring due to oilmay be reduced.

Further, as the plurality of filter devices may be provided in thecompressor, foreign substances or oil contained in the compressed gas(or discharge gas) introduced to the outside of the piston may beprevented from being introduced into the nozzle of the cylinder. Moreparticularly, the first filter may be provided on the suction muffler toprevent the foreign substances contained in the refrigerant from beingintroduced into the compression chamber. Also, the second filter may beprovided on the coupling between the cylinder and the frame to preventthe foreign substances and oil contained in the compressed refrigerantgas from flowing into the gas inflow of the cylinder.

Also, the third filter may be provided on the gas inflow of the cylinderto prevent the foreign substances and oil from being introduced into thenozzle of the cylinder from the gas inflow. Additionally, the filterdevice may be provided in the dryer provided in the refrigerator tofilter the moisture, foreign substances, or oil contained in therefrigerant.

As described above, as foreign substances or oil contained in thecompression gas that acts as a bearing may be filtered through theplurality of filtering devices provided in the compressor and dryer, itmay prevent the nozzle of the cylinder from being blocked by the foreignsubstances or oil. As the blocking of the nozzle of the cylinder isprevented, a gas bearing effect may be effectively performed between thecylinder and the piston, and thus, abrasion of the cylinder and thepiston may be prevented.

Embodiments disclosed herein provide a linear compressor in which a gasbearing may easily operate between a cylinder and a piston, and arefrigerant including a linear compressor.

Embodiments disclosed herein provide a linear compressor that mayinclude a shell including a suction inlet; a cylinder provided in theshell to define a compression space for a refrigerant; a pistonreciprocated in an axial direction within the cylinder; a dischargevalve provided on or at one side of the cylinder to selectivelydischarge the refrigerant compressed in the compression space; a nozzlepart or nozzle disposed in the cylinder to introduce at least a portionof the refrigerant discharged through the discharge valve into thecylinder; and a filter device or filter provided in the shell. Thefilter device may include at least one filter member disposed on or in arefrigerant passage defined from the suction inlet to the nozzle partvia the discharge valve. Foreign substances or oil contained in therefrigerant to be introduced into the nozzle part may be filtered whilepassing through the at least one filter member.

The linear compressor may further include a suction muffler provided inthe shell to reduce noise of the refrigerant suctioned through thesuction inlet. The filter device may include a first filter provided onthe suction muffler. The suction muffler may include a first muffler anda second muffler, and the first filter may be disposed at a coupledportion between the first and second mufflers.

The linear compressor may further include a groove part or groovedefined in one of the first muffler or the second muffler, and aprotrusion disposed on the other one of the first muffler or the secondmuffler. The protrusion may be coupled to the groove part. Both sides ofthe first filter may be disposed between the groove part and theprotrusion.

The first filter may include a magnetic material. The first filter maybe formed of a stainless steel material.

The linear compressor may further include a frame fixed to an outside ofthe cylinder. The filter device may include a second filter disposed ina refrigerant flow space between the cylinder and the frame.

The cylinder may include a cylinder body, and a cylinder flange part orflange that extends in a radial direction of the cylinder body. A recesspart or recess, in which the cylinder flange part may be inserted, and aseat part or seat, on which one surface of the cylinder flange part maybe seated, may be provided on the frame.

The second filter may be placed on the seat part of the frame. Thesecond filter may be placed between an outer circumferential surface ofthe cylinder flange part, and an inner circumferential surface of therecess part. The second filter may have a ring shape. Further, thesecond filter may include a felt formed of polyethylene terephthalate(PET) fiber.

The linear compressor may further include a gas inflow part or gasinflow recessed from an outer circumferential surface of the cylinder tocommunicate with the nozzle part. The filter device may include a thirdfilter disposed on or in the gas inflow part. The third filter mayinclude a thread having a preset or predetermined thickness or diameter.The thread may be formed of a polyethylene terephthalate (PET) material.The thread may be wound several times around the gas inflow part.

Embodiments disclosed herein further provide a refrigerator that mayinclude a linear compressor including a reciprocating piston and acylinder to accommodate the piston and having an outer circumferentialsurface to introduce a refrigerant; a filter device provided in thelinear compressor to filter the refrigerant introduced through the outercircumferential surface of the cylinder; a condenser to condense therefrigerant compressed in the linear compressor; and a dryer to removeforeign substances or oil contained in the refrigerant condensed in thecondenser. The dryer may include an adsorbent to adsorb the oilcontained in the refrigerant. The adsorbent may include a molecularsieve having a grain shape and a plurality of holes to adsorb the oil.The adsorbent may include an oil adsorbent paper or felt.

The dryer may include a first dryer filter disposed within an inlet-sideof the dryer; a second dryer filter that supports the first dryerfilter, the second dryer filter including the adsorbent; and a thirddryer filter that supports the second dryer, the third dryer filterbeing disposed within an outlet-side of the dryer.

The filter device may include a first filter including a suction mufflerto reduce flow noise of the refrigerant suctioned into the linearcompressor. The filter device may include a second filter disposed onone side of the cylinder to filter at least a portion of the refrigerantdischarged from the cylinder. The filter device may include a thirdfilter wound around the outer circumferential surface of the cylinder.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment. The appearances ofsuch phrases in various places in the specification are not necessarilyall referring to the same embodiment. Further, when a particularfeature, structure, or characteristic is described in connection withany embodiment, it is submitted that it is within the purview of oneskilled in the art to effect such feature, structure, or characteristicin connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A linear compressor, comprising: a shellcomprising a suction inlet; a cylinder provided in the shell to define acompression space for a refrigerant; a piston reciprocated in an axialdirection within the cylinder; a discharge valve provided at one end ofthe cylinder to selectively discharge the refrigerant compressed in thecompression space; at least one nozzle disposed in the cylinder tointroduce at least a portion of the refrigerant discharged through thedischarge valve into the cylinder; and at least one filter provided inthe shell, wherein the at least one filter is installed in a refrigerantpassage that extends from the suction inlet to the at least one nozzlevia the discharge valve, and wherein foreign substances or oil containedin the refrigerant to be introduced into the at least one nozzle arefiltered while passing through the at least one filter.
 2. The linearcompressor according to claim 1, further comprising a suction mufflerprovided in the shell to reduce noise of the refrigerant suctioned inthrough the suction inlet, wherein the at least one filter comprises afilter installed in the suction muffler.
 3. The linear compressoraccording to claim 2, wherein the suction muffler comprises a firstmuffler and a second muffler, and wherein the filter is installedbetween the first muffler and the second muffler.
 4. The linearcompressor according to claim 3, further comprising: a groove formed inone of the first muffler or the second muffler; and a protrusionprovided at the other one of the first muffler or the second muffler,wherein the protrusion is coupled to the groove, and wherein the filteris interposed between the groove and the protrusion.
 5. The linearcompressor according to claim 2, wherein the filter comprises a magneticmember.
 6. The linear compressor according to claim 2, wherein thefilter is formed of a stainless steel material.
 7. The linear compressoraccording to claim 1, further comprising a frame installed to an outsideof the cylinder, wherein the at least one filter comprises a filterinstalled in a space between the cylinder and the frame.
 8. The linearcompressor according to claim 7, wherein the cylinder comprises acylinder body and a cylinder flange that extends in a radial directionof the cylinder body, and wherein the frame comprises a recess in whichthe cylinder flange is inserted, and a seat, on which a surface of thecylinder flange is seated.
 9. The linear compressor according to claim8, wherein the filter is positioned on the seat of the frame.
 10. Thelinear compressor according to claim 8, wherein the filter is positionedbetween an outer circumferential surface of the cylinder flange and aninner circumferential surface of the recess.
 11. The linear compressoraccording to claim 7, wherein the filter has a ring shape.
 12. Thelinear compressor according to claim 7, wherein the filter comprises afelt formed of polyethylene terephthalate (PET) fiber.
 13. The linearcompressor according to claim 1, further comprising at least one gasinflow recessed from an outer circumferential surface of the cylinder tocommunicate with the at least one nozzle, wherein the at least onefilter comprises a filter installed in the at least one gas inflow. 14.The linear compressor according to claim 13, wherein the filtercomprises a thread having a predetermined thickness or diameter.
 15. Thelinear compressor according to claim 14, wherein the thread is formed ofa polyethylene terephthalate (PET) material.
 16. The linear compressoraccording to claim 14, wherein the thread is wound several times aroundthe at least one gas inflow.
 17. A refrigerator, comprising: a linearcompressor comprising a reciprocating piston and a cylinder thataccommodates the piston and having an outer circumferential surfacethrough which a refrigerant is introduced; at least one filter providedin the linear compressor to filter the refrigerant introduced throughthe outer circumferential surface of the cylinder; a condenser thatcondenses the refrigerant compressed in the linear compressor; and adryer to remove foreign substances or oil contained in the refrigerantcondensed in the condenser, wherein the dryer comprises an adsorbent toadsorb the oil contained in the refrigerant.
 18. The refrigeratoraccording to claim 17, wherein the adsorbent comprises a molecular sieveprovided with a plurality of holes to adsorb the oil, the adsorbenthaving a grain shape.
 19. The refrigerator according to claim 17,wherein the adsorbent comprises an oil adsorbent paper or felt.
 20. Therefrigerator according to claim 17, wherein the dryer comprises: a firstdryer filter disposed within an inlet-side of the dryer; a second dryerfilter supported by the first dryer filter, the second dryer filtercomprising the adsorbent; and a third dryer filter that supports thesecond dryer, the third dryer filter being disposed within anoutlet-side of the dryer.
 21. The refrigerator according to claim 17,wherein the at least one filter comprises a filter installed at asuction muffler that reduces flow noise of the refrigerant suctionedinto the linear compressor.
 22. The refrigerator according to claim 17,wherein the at least one filter comprises a filter disposed at one endof the cylinder to filter at least a portion of the refrigerantdischarged from the cylinder.
 23. The refrigerator according to claim17, wherein the at least one filter comprises a filter wound around theouter circumferential surface of the cylinder.
 24. A linear compressor,comprising: a shell comprising a suction inlet; a cylinder provided inthe shell to define a compression space for a refrigerant; a pistonreciprocated in an axial direction within the cylinder; a dischargevalve provided at one end of the cylinder to selectively discharge therefrigerant compressed in the compression space; at least one nozzledisposed in the cylinder to introduce at least a portion of therefrigerant discharged through the discharge valve into the cylinder;and a plurality of filters installed along a refrigerant passage thatextends from the suction inlet to the at least one nozzle via thedischarge valve, wherein foreign substances or oil contained in therefrigerant to be introduced into the at least one nozzle are filteredwhile passing through the plurality of filters.
 25. The linearcompressor according to claim 24, wherein the plurality of filterscomprises a first filter installed in a suction muffler provided in theshell to reduce noise of the refrigerant suctioned in through thesuction inlet.
 26. The linear compressor according to claim 25, whereinthe suction muffler comprises a first muffler and a second muffler, andwherein the filter is installed between the first muffler and the secondmuffler.
 27. The linear compressor according to claim 25, wherein theplurality of filters further comprises a second filter installed betweenthe cylinder and a frame installed at an outside of the cylinder. 28.The linear compressor according to claim 27, wherein the cylindercomprises a cylinder body and a cylinder flange that extends in a radialdirection of the cylinder body, and wherein the frame comprises a recessin which the cylinder flange is inserted, and a seat, on which a surfaceof the cylinder flange is seated, and wherein the second filter ispositioned on the seat of the frame.
 29. The linear compressor accordingto claim 27, further comprising at least one gas inflow recessed from anouter circumferential surface of the cylinder to communicate with the atleast one nozzle, wherein the plurality of filters further comprises athird filter installed in the at least one gas inflow.
 30. The linearcompressor according to claim 29, wherein the filter comprises a threadhaving a predetermined thickness or diameter.